package com.xlz.myapplication;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Base64;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

//对称加密
//DES(8位),AES(16位)，3DES(24位)
public class Encrption extends AppCompatActivity {
    //输入加密的内容，和密码
    private EditText input,pw;
    //显示加密后的内容
    private TextView showInfo;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_encrption);

        initView();
    }

    private void initView() {
        input=(EditText) findViewById(R.id.input);
        pw=(EditText) findViewById(R.id.pw);
        showInfo=(TextView) findViewById(R.id.showInfo);
    }

    //加密的点击事件
    //加密结果
    private String encryptResult=null;
    public void encrypt(View view) {
        String data = input.getText().toString().trim();
        String pw = this.pw.getText().toString().trim();

        String decryptResult=null;
        switch (view.getId()){
            case R.id.desEncrypt://加密
                //需要类型，要加密的内容
                encryptResult=encrypt("DES",data, pw);
                showInfo.setText("DES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.desDecrypt://DES解密
               decryptResult=decrypt("DES",encryptResult,pw);
                showInfo.setText("DES解密的内容是："+encryptResult+",解密的结果是："+decryptResult);
                break;
            case R.id.desedeEncrypt://3DES加密
                //密码长度为24位
                encryptResult=encrypt("DESede",data, pw);
                showInfo.setText("3DES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.desedeDecrypt://3DES解密
                decryptResult=decrypt("DESede",encryptResult,pw);
                showInfo.setText("3DES解密的内容是："+encryptResult+",解密的结果是："+decryptResult);
                break;
            case R.id.aesEncrypt://AES加密
                //密码长度为16位
                encryptResult=encrypt("AES",data, pw);
                showInfo.setText("AES加密的内容是："+data+",加密的结果是："+encryptResult);
                break;
            case R.id.aesDecrypt://AES解密
                decryptResult=decrypt("AES",encryptResult,pw);
                showInfo.setText("AES解密的内容是："+encryptResult+",解密的结果是："+decryptResult);
                break;

        }
    }

    //解密的方法
    private String decrypt(String type, String data, String pw) {
        switch (type){
            case "DES":
                //1、获取解密对应的类,解密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对解密引擎初始化，指定密码

                    if(pw.getBytes().length!=8){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.DECRYPT_MODE,key);

                    //3、执行解密
                    if(!TextUtils.isEmpty(data)){
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base64编码
                        //Base64解码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        //解密原始内容
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        //返回数据
                        return new String(decryptBytes);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }


                break;
            case "DESede":

                //1、获取解密对应的类,解密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对解密引擎初始化，指定密码

                    if(pw.getBytes().length!=24){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.DECRYPT_MODE,key);

                    //3、执行解密
                    if(!TextUtils.isEmpty(data)){
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base64编码
                        //Base64解码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        //解密原始内容
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        //返回数据
                        return new String(decryptBytes);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            case "AES":

                //1、获取解密对应的类,解密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对解密引擎初始化，指定密码

                    if(pw.getBytes().length!=16){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.DECRYPT_MODE,key);

                    //3、执行解密
                    if(!TextUtils.isEmpty(data)){
                        //Base64逆运算，加密时，为了内容不乱码，进行了Base64编码
                        //解密的内容，就是经过Base64编码
                        //Base64解码
                        byte[] base64Decode = Base64.decode(data.getBytes(), Base64.DEFAULT);
                        //解密原始内容
                        byte[] decryptBytes = cipher.doFinal(base64Decode);
                        //返回数据
                        return new String(decryptBytes);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            default:
                try {
                    throw new Exception("加密的类型不匹配，请选择以下几种加密类型：DES,AES,DESede");
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;

        }


        return null;


    }

    //加密有三种方式
    private String encrypt(String type, String data, String pw) {
        switch (type){
            case "DES":
                //1、获取加密对应的类,机密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对加密引擎初始化，指定密码

                    if(pw.getBytes().length!=8){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.ENCRYPT_MODE,key);

                    //3、执行加密
                    if(!TextUtils.isEmpty(data)){
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());
                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);
                        return new String(base64Encode);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }


                break;
            case "DESede":

                //1、获取加密对应的类,机密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对加密引擎初始化，指定密码

                    if(pw.getBytes().length!=24){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.ENCRYPT_MODE,key);

                    //3、执行加密
                    if(!TextUtils.isEmpty(data)){
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());
                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);
                        return new String(base64Encode);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            case "AES":

                //1、获取加密对应的类,机密引擎
                try {
                    Cipher cipher=Cipher.getInstance(type);

                    //2、对加密引擎初始化，指定密码

                    if(pw.getBytes().length!=16){
                        throw new Exception("密码长度必须是8位");
                    }
                    Key key =new SecretKeySpec(pw.getBytes(),type);
                    cipher.init(Cipher.ENCRYPT_MODE,key);

                    //3、执行加密
                    if(!TextUtils.isEmpty(data)){
                        byte[] encryptBytes = cipher.doFinal(data.getBytes());
                        byte[] base64Encode = Base64.encode(encryptBytes, Base64.DEFAULT);
                        return new String(base64Encode);
                    }


                } catch (NoSuchAlgorithmException e) {
                    e.printStackTrace();
                } catch (NoSuchPaddingException e) {
                    e.printStackTrace();
                } catch (InvalidKeyException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                }

                break;
            default:
                try {
                    throw new Exception("加密的类型不匹配，请选择以下几种加密类型：DES,AES,DESede");
                } catch (Exception e) {
                    e.printStackTrace();
                }
                break;

        }


        return null;
    }
}
